Heavy metal (HM) contamination in agricultural soils poses a critical threat to food safety, particularly in vegetable production systems where direct human exposure occurs through consumption. Vegetables grown in contaminated soils often accumulate elevated levels of toxic metals such as lead, cadmium, chromium, and arsenic, as well as excessive zinc, increasing dietary and public health risks. Conventional remediation methods are frequently costly, inefficient, or environmentally unsustainable. Biochar has emerged as a promising, sustainable amendment for reducing HM bioavailability; however, its effectiveness and mechanisms in vegetable-growing soils remain insufficiently understood. This review critically evaluates biochar’s remediation potential, associated risks, and practical challenges, and outlines future research and policy priorities for safe and sustainable vegetable production. While biochar’s physicochemical traits—such as high surface area, alkalinity, and cation exchange capacity—facilitate metal immobilization through adsorption, ion exchange, and precipitation, remediation outcomes vary widely with production conditions and application rates. Potential drawbacks include nutrient immobilization or the remobilization of elements such as arsenic and chromium (VI). Broader adoption is further limited by variability in biochar quality, scarce long-term field data, high production costs, and weak policy support. Strengthening biochar governance through quality standards, financial incentives, and integration into soil health and carbon sequestration programs is essential to enhance feasibility and farmer adoption. By linking scientific evidence with policy and practice, biochar can serve as a scalable solution for safer vegetable production, improved soil resilience, and climate change mitigation.
Le et al. (Sat,) studied this question.